Morphometric measurements for sexual dimorphism in the Campolina horse breed

Krebs, Lisia Castro; Santos, Marina Monteiro de Moraes; Siqueira, Maria Claudia; Araujo, Brennda Paula Gonçalves de; Oliveira, Leonardo Gomes; Feitosa, Fabiany Sousa Costa; Camargo, Gregório Miguel Ferreira de; Oliveira, Chiara Albano de Araújo; Costa, Raphael Bermal; Schultz, Erica Beatriz; Godoi, Fernanda Nascimento de

doi:10.1590/S1678-3921.pab2021.v56.02148

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Animal Science • Pesq. agropec. bras. 56 • 2021 • https://doi.org/10.1590/S1678-3921.pab2021.v56.02148 copy

Morphometric measurements for sexual dimorphism in the Campolina horse breed

Medidas morfométricas para o dimorfismo sexual em equinos da raça Campolina

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract:

The objective of this work was to distinguish the sexual dimorphism of horses of the Campolina breed, by morphometric measurements, and to classify them according to sex, using discriminating functions. Two-hundred and fifteen horses were measured, and 39 morphometric measurements were evaluated. The analysis of covariance and the discriminant analysis were performed. Males were taller and showed a wider chest, a greater scapular-humeral angle, and a larger neck, both in length and circumference. Females had a larger heart girth, wider hips, and a greater opening of the coxal-ground and femorotibial angles. Regarding classification, circumference measurements (85.58%) were more accurate in sexual differentiation than the linear (83.26%) and angular (73.02%) ones. As to classification error, of the total animals measured, 10 to 20% of the females were categorized as males. In addition, 11 to 38% of the males were categorized as females. It can be concluded that of the 39 morphometric measurements evaluated, 22 are responsible for sexual dimorphism in the Campolina horse breed. Circumference and linear measurements provide a more assertive classification to determine sexual dimorphism. Angular measurements show greater classification errors regarding the gender of the horses.

Index terms:
Equus caballus; equine morphology; multivariate analysis

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[1] *Corresponding author

Morphometric measurements (m)	Male	Female	SEM⁽¹⁾	p-value
Wither height	1.566	1.533	0.33	<0.001*
Croup height	1.545	1.528	0.28	<0.002*
Chest depth	0.715	0.707	0.23	0.073
Body length	1.609	1.603	0.37	0.439
Head length	0.610	0.604	0.18	0.090
Ear length	0.180	0.183	0.07	0.027*
Ear width	0.651	0.661	0.05	0.289
Neck length	0.614	0.599	0.27	0.006*
Shoulder length	0.493	0.492	0.27	0.771
Arm length	0.334	0.331	0.18	0.453
Forearm length	0.447	0.450	0.14	0.230
Fore cannon length	0.281	0.274	0.12	0.005*
Fore pastern length	0.135	0.131	0.07	0.008*
Croup length	0.485	0.490	0.23	0.271
Thigh length	0.331	0.331	0.20	0.997
Leg length	0.546	0.526	0.25	<0.001*
Hind cannon length	0.331	0.332	0.15	0.906
Hind pastern length	0.136	0.134	0.07	0.131
Shoulder-fetlock distance	0.675	0.666	0.18	0.014*
Sternum-ground distance	0.851	0.826	0.20	<0.001*
Chest width	0.403	0.394	0.21	0.037*
Hip width	0.493	0.504	0.25	0.022*

Morphometric measurements (m)	Male	Female	SEM⁽¹⁾	p-value
Heart girth	1.799	1.837	0.83	0.022*
Cranial neck circumference	0.815	0.779	0.39	<0.001*
Caudal neck circumference	1.299	1.154	0.85	<0.001*
Forehead circumference	0.879	0.896	0.23	<0.001*
Nasal bridge circumference	0.628	0.630	0.31	0.704
Forearm circumference	0.330	0.323	0.14	0.019*
Knee circumference	0.307	0.310	0.12	0.296
Fore cannon circumference	0.187	0.195	0.11	<0.001*
Fore fetlock circumference	0.262	0.270	0.12	0.002*
Fore pastern circumference	0.183	0.192	0.09	<0.001*

Morphometric measurements (º)	Male	Female	SEM⁽¹⁾	p-value
Scapula-ground angle	68.57	68.15	0.32	0.520
Scapulohumeral angle	89.60	87.22	0.35	<0.001*
Humeroradial angle	142.86	141.66	0.34	0.081
Coxal-ground angle	27.62	31.98	0.33	<0.001*
Coxofemoral angle	87.17	88.34	0.46	0.241
Femorotibial angle	110.54	113.09	0.43	<0.001*
Tibiometatarsal angle	141.73	140.89	0.26	0.109

Item	Female	Male	Total
Number of females	117	14	131
Classification (%)	89.31	10.69⁽²⁾	100
Number of males	22	62	84
Classification (%)	26.19⁽²⁾	73.81	100

Item	Female	Male	Total
Number of females	110	21	131
Classification (%)	83.97	16.03⁽²⁾	100
Number of males	10	74	84
Classification (%)	11.90⁽²⁾	88.09	100